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Topic: Beta carbon nitride

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In the News (Mon 18 Feb 19)

  Carbon - Wikipedia
Carbon is a chemical element in the periodic table that has the symbol C and atomic number 6.
Carbon is a vital component of all known living systems, and without it life as we know it could not exist (see carbon chauvinism).
The most prominent oxide of carbon is carbon dioxide, CO This is a minor component of the Earth's atmosphere, produced and used by living things, and a common volatile elsewhere.
www.facetroughgemstones.com /wikipedia/ca/Carbon.html   (1554 words)

 Carbon - Facts, Information, and Encyclopedia Reference article
Carbon is a vital component of all known living systems, and without it life as we know it could not exist (see alternative biochemistry).
Carbon is used as a neutron moderator in nuclear reactors.
Carbon is abundant in the sun, stars, comets, and in the atmospheres of most planets.
www.startsurfing.com /encyclopedia/c/a/r/Carbon.html   (2155 words)

 Beta carbon nitride: Definition and Links by Encyclopedian.com
...Beta carbon nitride Beta carbon nitride Beta carbon nitride (β-C 3 N 4)...that block these beta 1 receptors therefore have the opposite effect: they lower the heart rate...
...a currently hypothetical material, beta carbon nitride, may also be as hard or harder in one form.The diamond...accompanied by 2 additional weak green bands.
Examining the nature of crystalline bonds they theorised that carbon and nitrogen atoms could form a particularly short and strong bond in a stable lattice in a ratio of 1:1.3.
www.encyclopedian.com /be/Beta-carbon-nitride.html   (263 words)

Diamond is one of the natural allotropes of carbon (the main one being graphite).
The material boron nitride, when in a form structurally identical to diamond, is nearly as hard as diamond; a currently hypothetical material, beta carbon nitride, may also be as hard or harder in one form.
In the late 18th century, diamonds were demonstrated to be made of carbon by the rather expensive experiment of igniting a diamond (by means of a burning-glass) in an oxygen atmosphere and showing that carbonic acid gas (carbon dioxide) was the product of the combustion.
www.ebroadcast.com.au /lookup/encyclopedia/di/Diamond.html   (1204 words)

 Boron nitride Information Center - boron nitride powder
Boron nitride is a binary chemical boron nitride dispersant compound, consisting of equal proportions of boron and nitrogen, with formula boron nitride uses BN.
Hexagonal boron nitride is produced by the nitridation or ammonolysis boron nitride and gasketing of boron trioxide.
Cubic boron nitride is produced boron nitride synthesis by treating boron nitride supplier dry lubricant boron nitride prices boron nitride hexagonal boron nitride combat boron nitride at high pressure and temperature, much as synthetic diamond is produced from graphite.
www.scipeeps.com /Sci-Chemistry_Topics_Ap_-_B/Boron_nitride.html   (241 words)

 Preparation of nitride and carbide from inorganic-organic polymer complex - Patent 4652436
Other carbides or nitrides are prepared in the form of powder through a macroscopical contact of powder solids although the vapor phase reaction is employed when they are produced in the form of whisker.
It may be summarized from the above that synthesis of carbide or nitride powder depends on a reaction among solid particle surfaces of a material mixture caused by calcination of the mixture at high temperature, or a reaction of the sublimed gaseous components or a thermal decomposition reaction thereof.
Where a polymerized or condensed organic substance is intercalated into the spaces, hydrocarbon and carbon monoxide formed due to the thermal decomposition at high temperature keep the interior of the reaction furnace under a reducing atmosphere, and the remaining carbon becomes a raw material for carbide.
www.freepatentsonline.com /4652436.html   (5123 words)

 Carbon Info - Bored Net - Boredom   (Site not responding. Last check: 2007-10-13)
Crude oil is used by the petrochemical industry to produce, amongst others, petroleum, gasoline and kerosene, through a distillation process, in so-called refineries.
It is, rather, present as a powder which is the main constituent of substances such as charcoal and lamp fl (soot).
Diamond has the same cubic structure as silicon and germanium and, thanks to the strength of the carbon-carbon bondss, is together with the isoelectronic boron nitride (BN) the hardest substance in terms of resistance to scratching.
www.borednet.com /e/n/encyclopedia/c/ca/carbon.html   (1605 words)

 Boron Nitride - Properties & Applications and Supplier of Boron Nitride,   (Site not responding. Last check: 2007-10-13)
In inert and reducing atmospheres, Boron Nitride will withstand temperatures over 2,000°C. It is not wet by most molten metals and slags and can therefore be used as a container for most molten metals including aluminium, cryolite, sodium, iron, steel, silicon, boron, tin germanium and copper.
Boron Nitride is a binary chemical compound, consisting of equal proportions of boron and nitrogen, with composition BN.
Nitrides are binary salt-like compounds of nitrogen, usually with metals.
www.precision-ceramics.co.uk /boron_nitride.htm   (372 words)

 In ancient times a relatively small number of men produced steel
Carbon steels are by far the most produced and used, accounting for about 90 percent of the world's steel production.
Carbon steels are also defined as having less than 1.65- percent manganese, 0.6 percent silicon, and 0.6 percent copper, with the total of these other elements not exceeding 2 percent.
The level of dissolved oxygen in liquid steel must be lowered because oxygen reacts with carbon during solidification and forms carbon monoxide and blowholes in the cast.
www.eng.morgan.edu /~dswann/IEGR363/steel.htm   (5069 words)

 Process for producing beta silicon nitride fibers - Patent 4717693
Since the beta silicon nitride phase is the high temperature stable phase for silicon nitride, it is the desired phase for use in ceramics, ceramic composites or as fibrous material for use as a thermal barrier coating or tile.
The result is coarse flat whiskers of beta silicon nitride with a light greenish tint suggestive of microfine silicon carbide but not as fine as the fibers produced in Example 1.
The result is that the external surface of the silicon nitride preform is covered with silicon carbide "fuzz" and the exterior of the crucible appears to be converted to a very thin layer of polycrystalline silicon carbide.
www.freepatentsonline.com /4717693.html   (1660 words)

 The Element Carbon -- Carbon Atom
In the simple form 60 carbon atoms form a graphitic layer which is bent to a 3-dimensional structure, similar to a soccer ball.
So-called 'glassy carbon' is isotropic and as strong as glass.
Carbon is a vital component of all known living systems, and without it life as we know it could not exist (see
www.worldofmolecules.com /elements/carbon.htm   (1309 words)

 Diamond Chemistry and Composition   (Site not responding. Last check: 2007-10-13)
Diamonds are formed when carbon deposits are exposed to high pressure and temperature for prolonged periods.
Diamond is one of several allotropes of carbon, the principle allotrope being graphite.
The material "boron nitride", when in a form structurally identical to diamond, is nearly as hard as diamond.
www.khulsey.com /jewelry/kh_jewelry_diamond_chemistry.html   (1485 words)

 Silicon Carbide
Beta silicon carbide takes the diamond cubic structure with half of the carbons being replaced with silicon; this is a very stable structure that is conducive to phononic heat conduction.
Alpha silicon nitride is the more common form of silicon nitride and occurs in a hexagonal close-packed structure with the SiC tetrahedra half-filled.
This is the form of SiC that is used in polishing paper and grinding media and is produced by the beta to alpha phase transformation that occurs at around 1500C to 1600C.
www.eden.rutgers.edu /~glock/academia/sic.html   (666 words)

 Boron Nitride Nanotubes More Amenable Than Carbon
However, different from their carbon analogues, boron nitride nanotubes are wide-gap semiconductors with a quasiparticle band gap of about 5.5 eV.
Boron nitride is far more resistant to oxidation than carbon and therefore suited for high temperature applications in which carbon nanostructures would burn.
Moreover, BN nanotubes electronic properties are independent of tube diameter and number of layers, unlike tubes made of carbon, making BN nanotubes much more amenable: by doping these tubes, it is conceivable to have devices on single BN tubes which have diameters on the order of nanometers and lengths on the order of microns.
www.physorg.com /news92.html   (891 words)

 Arklay S. Richards - Products
Nitride bonded silicon carbide tubes (SCN) have the same characteristics as Oxide bonded silicon carbide with a few exceptions.
Isopressed or Carbon bonded silicon carbide tubes (SCI) are less porous (8%) than Nitride bonded silicon carbide but not as dense as Oxide or Nitride bonded tubes.
Carbon bonded silicon carbide tubes (SCI) are less porous (8%) than Nitride bonded silicon carbide but not as dense as Oxide or Nitride bonded tubes.
www.asrichards.com /sensor_silicon_carbide.htm   (592 words)

 SPIE Proceedings Vol. 3550   (Site not responding. Last check: 2007-10-13)
Abstract: Carbon nitride films were synthesized by active atomic nitrogen beams intersecting pulsed laser plumes at the substrates without heating.
Abstract: Carbon nitride thin films were deposited on silicon wafers by pulsed KrF Excimer (wavelength 248 nm, duration 23 ns) ablation of graphite.
Carbon precipitated in zeolites using this method has shown a broad absorption band located at 3.0 eV which is lower photon energy than that of benzene, Furthermore, a visible photoluminescence (PL) band with a peak around 2.0 eV has been observed at room temperature.
www.spie.org /web/abstracts/3500/3550.html   (10360 words)

 Harder than Diamond
Beta carbon nitride (β-C3N4) is a theoretical material, derived from theories on crystalline structure.
It is thought that beta carbon nitride will have a hardness value, if harder than diamond, less than that of ultrahard fullerite.
One example, perhaps surprisingly, is diamond, provided it has been appropriately "cooked".
www.24carat.co.uk /harderthandiamond.html   (622 words)

 Boron nitride - Wikipedia, the free encyclopedia
Boron nitride can be used to make crystals that are extremely hard, second in hardness only to diamond, and the similarity of this compound to diamond extends to other applications.
This form of boron nitride is composed of layers of fused hexagonal sheets (analogous to graphite).
The polar B-N bonds interfere with electron transfer so that boron nitride in this form is not an electrical conductor (in contrast to graphite which is a semimetal that conducts electricity through a network of pi bonds in the plane of its hexagonal sheets).
en.wikipedia.org /wiki/Boron_nitride   (1301 words)

 MatSci In The News - Materials Science and Engineering - Northwestern University
The researchers made alternating thin layers of carbon nitride and titanium nitride using a process called magnetron sputtering, in which molecules of gas are fired at a solid target.
Titanium nitride and non-crystalline carbon nitride are both hard, but the composite material was twice as hard as either.
Titanium nitride forms crystals easily, and Chung suggests that carbon nitride may somehow be forced to crystallise when sandwiched between layers of a titanium nitride crystal lattice.
www.matsci.northwestern.edu /new.html   (11991 words)

 LBL Scientists Awarded Patent on Superhard Material   (Site not responding. Last check: 2007-10-13)
The new superhard carbon- nitrogen compound could serve as an inexpensive substitute for diamond, or it could be used to carve diamonds into intricate shapes for use as semiconductors in electronic devices.
A plasma containing carbon and nitrogen ions was created and then deposited as a thin film over the surface of a silicon wafer.
Says Haller, "The trick is to get the carbon and nitrogen ions to recombine so that their bond lengths are quite short and the stiffness of the bonds (the energy it takes to break them) is as high as that of diamond.
www.lbl.gov /Science-Articles/Archive/superhard-materials.html   (717 words)

 As hard as diamond? Tracking the elusive carbon nitride - Cover Story Science News - Find Articles
In a diamond, the carbon atoms arrange themselves in a rigid crystal structure, whereas in graphite, the atoms form slippery, flat sheets.
They had hoped to get carbon nitride crystals, which they expected to be a new hard material, but they invariably ended up with diamonds, says David M. Teter of Virginia Tech in Blacksburg.
Steel itself is primarily a mixture of iron and carbon, and at high temperatures, "iron acts like a sponge for carbon," says Chung.
findarticles.com /p/articles/mi_m1200/is_n2_v154/ai_20973050?...   (881 words)

Carbon fiber is used with aluminum alloys; however, at typical fabrication temperatures of 500'C or higher, carbon reacts with aluminum to form aluminum carbide (Al), which severely degrades the mechanical properties of the composite.
Carbon fiber-reinforced aluminum composites are inherently prone to galvanic corrosion, in which carbon fibers act as a cathode owing to a corrosion potential of 1 V higher than that of aluminum.
Continuous carbon fiber-reinforced PEEK composites are known in the industry as aromatic polymer composite or APC.
www.eng.uab.edu /epcl/c_matrix.htm   (5092 words)

 Geek.com Geek News - Berkeley scientists create a chip with nanotube transistors
They're called carbon nanotubes because graphite is a particular arrangement of carbon atoms.
Carbon nitride still only exists as nanocrystaline material, deposited on silicon substrate through plasma CVD process.
Boron nitride and diamond can be argued endlessly as to which is harder.
www.geek.com /news/geeknews/2003Dec/bch20040106023334.htm   (1711 words)

 Session EMP4 - Poster Session: Deposition.
Motivated by the desire to establish a nitridation environment with extremely high reactivity for the synthesis of this metastable covalent material, we have developed a sputtering deposition system with installation of high-density helicon wave-excited plasma source to supply high concentration of atomic nitrogen.
Carbon nitride films have been deposited on Si and WC substrates using reactive sputtering of carbon in N_2 and Ar mixture gas around 0.1 Pa. High-density plasmas of 10^12-10^13 /cm^3 were produced even in pure N_2 using a helical antenna, where the excitation of m=0 mode helicon wave was verified to propagate.
It is found that carbon films substantially deposited on reactor walls significantly influence on diamond nucleation and growth using magneto-active microwave plasma CVD, indicating that carbon-related sources originated from the unintentionally deposited materials on the chamber wall and substrate holder make an important effect to nucleation density and growth rate and quality of diamond films.
flux.aps.org /meetings/YR98/BAPSGEC98/abs/S1400.html   (4133 words)

 BBC - h2g2 - Mohs Scale of Hardness
Diamond is an allotrope of carbon and it is interesting to note that another allotrope of carbon, graphite, is one of the world's softest minerals.
Although it is possible to coat metals with a thin layer of diamond, it would be somewhat easier with a synthetic material such as beta-carbon nitride.
Another celebrated material is Borazon, a synthetic compound of boron and nitrogen, which was discovered by Dr R Wentorf in 1956.
www.bbc.co.uk /dna/h2g2/A2982576   (1072 words)

 Ledford Final   (Site not responding. Last check: 2007-10-13)
A hydrogen storage capacity of 4.2 weight percent, or a hydrogen to carbon atom ratio of 0.52, was achieved reproducibly at room temperature under a high pressure (about 10 megapascal) for a SWNT sample of about 500 milligram weight that was soaked in hydrochloric acid and then heat-treated in vacuum.
Engineers at the Chinese Academy of Science and the University of New York Buffalo have collaborated to produce aligned carbon nitride (C-N) nanobells in a polymer form.These structures were using silicon substaratesfrom the gas mixture on nitrogen and methane by microwave plasma assisted deposition.
Sung June Cho, a chemist at the Korean Institute of Energy Research, suspected that the storage capabilities of carbon nanotubes could be partly owing to their ability to conduct electrical charges, as this would cause the hydrogen to adhere.
thecollege.wlu.edu /research_service/RELee/Physics2003/LedfordFinal.asp   (3133 words)

 Welcome to UBCeram
Synthesized trough calcining barium carbonate and iron oxide, followed by solid-state diffusion and reaction to form the ferrite.
Synthesized trough calcining barium carbonate and titanium oxide, followed by solid-state diffusion and reaction to form the titanate.
Similar to barium titanate, synthesized trough calcining calcium carbonate and titanium oxide, followed by solid-state diffusion and reaction to form the titanate.
www.ceramics.mmat.ubc.ca /int/KCM.html   (4808 words)

 About Diamonds -- Properties and Molecular Structure
Sometimes known as adamant, it is the hardest known naturally occurring material, scoring 10 on the old Mohs scale of mineral hardness.
Natural blue diamonds recently recovered from the Argyle mine in Australia have been found to owe their color to an overabundance of hydrogen atoms: these diamonds are not semiconductors.
At surface air pressure (one atmosphere), diamonds are not as stable as graphite, and so the decay of diamond is thermodynamically favorable (dH = -2 kJ / mole).
www.worldofmolecules.com /materials/diamond.htm   (788 words)

 A new route to a superhard material? - Brief Article Science News - Find Articles
For years, scientists have tried to synthesize beta-carbon nitride, a material predicted by theorists to be harder than diamond.
The Cornell theorists "propose a rather clever approach to the synthesis of hard [beta-carbon nitride] solids," says YipWah Chung of Northwestern University in Evanston, Ill. "Of course, the proof is in the pudding," he remarks.
The method will work only if beta-carbon nitride is more stable under high pressure than other carbon-nitrogen structures.
findarticles.com /p/articles/mi_m1200/is_23_155/ai_55017627?...   (308 words)

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